The present invention relates to compasses and particularly to a compass sensor and display.
Compasses for vehicles such as automobiles typically are aftermarket items of relatively basic design. Such compasses usually attach to the dashboard area of the vehicle and are of relatively inexpensive construction including a compass card suspended by a pin bearing and mounted within a housing. They include some elemental form of adjustment or compensation mechanism. In some cases the compasses include self-contained or vehicle battery powered lighting for night use.
On the other hand, relatively sophisticated compass equipment exists for commercial use typically in the marine environment. Such prior art is represented by, for example, U.S. Pat. Nos. 3,825,823; 3,833,901; 3,835,375; 3,888,016; 3,905,121; 3,906,483 and 3,959,899. In this prior art there is disclosed magnetically responsive sensing means including in some instances slotted discs forming optical encoders for providing digital signals to electrical circuitry which in turn responds to such signals for providing in some cases a numerical digital display of degrees representing the orientation of the sensor with respect to the earth's magnetic field.
The automotive environment is one which is particularly sensitive to changing electrical fields due to the relatively large number of electrical conductors in a car, the compactness of the vehicle and the changing state of actuation of the conductors. It has been discovered, however, that particular locations in a vehicle are well adapted for the placement of sensing means, which normally would not lend themselves to the mounting to prior art mechanical-type compasses. One such location is the center portion of the rear window ledge of a vehicle and another is behind the rear view mirror. The present invention incorporates a sensor which provides electrical signals which can be applied to a remote display such that the sensor location can be incorporated in conjunction with a digital display for use in a vehicle.